The present invention relates to a pressure sensor with a metal housing, with a closed-off and fluid-filled pressure space, with a diaphragm that partitions the pressure space off from the environment and transmit pressures derived therefrom to the fluid, with a pressure-sensitive chip of semiconducting material that is exposed to the pressure of the fluid and has a piezoresistant and anisotropic effect, and with connectors, metal rods for instance, that extend pressure-tight and electrically insulated from the metal housing into the pressure space and that can be connected to an electric processing circuit, whereby the pressure-sensitive chip is connected by bonds.
Pressure sensors of this type are known, from the KMK brochure, Sensoren und Messwert-Verarbeitungssysteme fur die Industrie for example. They are employed in pressure transducers. They have a special-steel housing in the form of a bolt with an outside thread and a hexagonal head. The partitioning diaphragm is mounted on the front. The pressure-sensitive chip is mounted on a base and connected to a processing circuit at the rear (outer end) of the sensor, and the connectors are insulated with glass.
There are disadvantages to pressure sensors of this type. It takes a lot of fluid, comparatively, to fill the pressure space. The glass insulation is expensive and leads to a high rate of rejection for the housings, which are made out of costly special steel. Even more expensive is the electric processing circuit for the transducer that accommodates the sensor, and it is impossible to test how well the transducers function until they are finished. Since the chip is mounted on a base, powerful impacts can snap it off because the shock wave can lead to excess pressure at the chip and to release of the pressure above it. If only a little fluid is employed in the pressure space in an attempt to improve the rating, the diaphragm can actually impact the chip when pressures are high enough. A highly significant drawback however is that the pressure within the pressure space increases along with temperature and acts on the chip, resulting in undesirable temperature-dependent errors in the instrumentation results.